The subject invention is directed toward the art of mechanical connectors and more particularly, to a screw thread connection of the "push-in" type.
The invention is especially suited for use in electrical junction and writing box structures to provide screw mountings for wiring devices and will be described with reference thereto; however, as will become apparent, the invention is capable of broader application and could be used in many different environments.
Electrical wiring boxes commonly include connections for facilitating the mounting of various wiring devices such as switches, electrical outlets and the like. The connections are typically simple threaded openings for receiving mounting screws. In certain designs, however, the openings have included resilient tabs or inserts to allow for "push-in" insertion of the mounting screws. Such arrangements are illustrated, for example, in U.S. Pat. Nos. 4,130,335, 4,069,448, 3,955,463 and 4,188,854.
In each of the known prior art arrangements a separate spring steel insert or multiple independent components are required As is apparent, these prior designs tend to increase the cost of the units Further, the use of the separate inserts requires an additional assembly step during the box manufacturing process.